Sage Modeler Guide: Slideshow
Below is a modeling software called "Sage Modeler." Some variables of the system are present and some connections are made for you. Use the slideshow linked above to learn more about specific actions you can do in this software, like adding arrows and labeling arrows.
1. Add other connections that are present in the system by adding arrows.
2. Define the arrows relationship. Once you do that, it should turn red (direct relationship) or blue (indirect relationship).
3. Label the arrows. The label should be the process the arrow represents, such as "evaporation."
Take a screenshot and upload the file below.